Evidence adduced over the past several years has clarified the molecular event responsible for malignant transformation in animal and human cancers. Work in my laboratory has focused on changes associated with human colorectal carcinogenesis. We and others have identified a number of oncogenes that are activated in human colon cancer. More recently work has focused on the role of growth factors acting in an autocrine or paracrine fashion to support the growth of colonic neoplasms. We have established that gastrin (a potent gastrointestinal growth hormone) is produced by colon cancer but not by normal colonic tissue and may stimulate the growth of these tumors. Using similar methodology, we plan to screen for endogenous production of other known potential growth factors. In order to facilitate this work, we need to organize the known human growth factors and cytokines into families based on sequence homology. This will enable us to design appropriate oligonucleotide primers for use in PCR (polmerase chain rection) of cDNA obtained from neoplastic and normal colon. Appropriate primer design will allow identification of both known and potentially novel but related growth factors produced in the colon.